Magnetostrictive or piezoelectric ultrasonic dental handpieces are used in dentistry to remove calculus from teeth and perform other cleaning or abrasive operations by vibrating a metal insert at an ultrasonic frequency. A dental handpiece typically receives electric current having a controlled frequency from a generator and translates the received electrical energy into a mechanical motion of the insert or a scaling tip. To this end, a magnetostrictive dental handpiece includes an electrical connector, a wire wound around a non-conducting shaft, and a housing functioning as a handle.
Ultrasonic dental handpieces may be autoclavable or non-autoclavable. Operators such as dentists or dental hygienists typically sterilize autoclavable handpieces by using steam or vaporized chemical solutions, frequently applied at a high pressure. For this reason, manufacturers typically make autoclavable handpieces detachable from their cord assemblies and/or the power generator unit. On the other hand, non-autoclavable handpieces do not tolerate high temperatures and are typically integrated with the cord assembly as well as with the power generator unit. Operators typically place disposable plastic covers over non-autoclavable handpieces to reduce contamination of the handpiece through contact with an operator's hand or with the detachable insert.
The ever-rising hygiene standards make autoclavable handpieces more preferable. Moreover, autoclavable handpieces are generally more convenient to use because they do not require temporary plastic covers. It is common knowledge that thin plastic material has a slippery feel and may interfere with the sense of a firm grip of a handle of an object, as well as reduce the overall comfort of holding the object.
Not surprisingly, autoclavable handpieces are more complex and more expensive that non-autoclavable handpieces. The manufacturing and maintenance of such handpieces also present several challenges related to protecting electrical components from heat and water damage. Today, there are several known approaches to manufacturing autoclavable handpieces. In accordance with one approach, an autoclavable handpiece includes a removable outer sheath or sleeve. An operator may sterilize the outer sheath without placing the entire handpiece into an autoclave. In an alternative approach, a handpiece includes crevices inside the housing in order to allow steam to pass through the handpiece. Unfortunately, none of these approaches allow both the convenience of sterilizing an entire handpiece without disassembly and a reliable degree of protection of the electrical components.
Further, users of electro-mechanical and magnetostrictive handpieces also find that because of the typical placement of electrical components, these handpieces are back-heavy and, as a result, cause discomfort after prolonged use. Moreover, because operators typically hold handpieces at a location closer to the scaling or cleaning tip (i.e., at the patient-proximate end), the weight of the back portion (or the patient-distal end) of the handpiece creates a significant torque making the operator's work even more tiring.
With respect to dental inserts, users of ultrasonic dental handpieces generally find it convenient to use various detachable inserts with a single handpiece. Understandably, users also prefer inter-manufacturer and inter-product compatibility and, as a result, expect inserts from different manufacturers to properly fit into the same handpiece. However, an insert designed to operate at a certain frequency may not operate properly if driven at a different frequency by the handpiece or, more precisely, by a power generator supplying electric current to the handpiece. To this end, it has been proposed to manufacture ultrasonic dental handpieces capable of adjusting the operational frequency to the particular type of insert. For example, a dental piece could drive the insert at one of the industry-standard frequencies of 25 KHz or 30 KHz, depending on the insert coupled to the handpiece. Unfortunately, this solution presents several significant challenges in production. Alternatively, some have suggested supplying dental handpieces with manual switches. A manual switch, however, similarly requires additional circuitry and increases the overall complexity of operating the handpiece. The user also needs to remember to check the type of insert and properly operate the switch to the appropriate setting or position.